/*
 * Copyright 2004-2005 The Apache Software Foundation or its licensors,
 *                     as applicable.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jackrabbit.core.query.lucene;

import java.io.IOException;

/**
 * <code>HierarchyResolver</code> extends an {@link org.apache.lucene.index.IndexReader}
 * with the ability to resolve a JCR hierarchy.
 */
public interface HierarchyResolver {

    /**
     * Returns the document number of the parent of <code>n</code> or
     * <code>-1</code> if <code>n</code> does not have a parent (<code>n</code>
     * is the root node).
     *
     * @param n the document number.
     * @return the document number of <code>n</code>'s parent.
     * @throws java.io.IOException if an error occurs while reading from the index.
     */
    public int getParent(int n) throws IOException;
}
